The present invention is related to an insulation material for use on subsea oil and gas production equipment.
When subsea oil and gas wells are located at depths of 5,000 feet or more, the pipelines and wellhead equipment are exposed to seawater which is just a few degrees above freezing. This same temperature can exist in shallow water at extreme latitudes, such as in the North Sea. During a temporary well shutdown, hot produced fluids within the production equipment become stagnant and are cooled by the surrounding seawater. If the stagnant fluids approach the seawater temperature, hydrates can form in the equipment and block the flow of the fluid.
Thermal insulation is sometimes installed around subsea pipelines and wellhead equipment to slow the cooling process and delay hydrate formation until flow can be restored. To perform successfully in this environment, a thermal insulation material must have a low thermal conductivity, exhibit acceptable mechanical properties such as flexibility and impact resistance, and be economical to install.
In many subsea wells, especially those in deep water, the insulation requirements are further complicated by the extreme temperatures of the hydrocarbon fluids exiting the well. In some cases the temperature of the exiting fluids may reach 300xc2x0 F. or higher, and the fluids will consequently heat both the surrounding equipment and the insulation. Therefore, any insulation material which is used on such wells must be able to withstand these extreme temperatures without detriment to its thermal or mechanical properties.
Although insulation materials exist which can withstand these relatively high temperatures, they are inherently brittle. Therefore, these materials are unable to meet the flexibility and impact resistance requirements of many applications. Examples of these types of prior art insulation materials include syntactic phenolic foams and high temperature epoxy resins. Furthermore, because of their brittle nature and exothermic curing properties, these materials are difficult and expensive to install and repair.
Conversely, existing insulation materials which exhibit acceptable flexibility and impact resistance characteristics are unable to withstand the relatively high flow temperatures present in may deep water wells. Examples of these types of prior art materials include amine cured epoxies, urethanes, and polypropylenes.
In accordance with the present invention, these and other disadvantages in the prior art are overcome by providing a thermal insulation material which comprises a silicone matrix and a plurality of non-metallic beads which are supported in the matrix. In one embodiment of the invention, the matrix comprises Silastic(copyright) E RTV silicone rubber, which is a platinum cured, addition cured silicone material. In addition, the non-metallic beads comprise hollow glass beads which have a mean diameter of less than about 60 microns and an isostatic strength of at least about 10,000 psi.
The thermal insulation material of the present invention exhibits many advantageous properties which make it particularly suitable for use on subsea oil and gas production equipment. The matrix material is highly flexible, which makes the insulation material resistant to cracking under thermal and mechanical stresses. In addition, since the matrix material produces no by-products or exothermic effects during curing, the insulation material can be cast-in-place in thick sections. Furthermore, due to its relatively low thermal conductivity, the insulation material is an excellent insulator. Moreover, the insulation material can withstand extreme temperatures in excess of 300xc2x0 F. without detriment to its thermal or mechanical properties.
These and other objects and advantages of the present invention will be made apparent from the following detailed description, with reference to the accompanying drawings.